This invention relates to high pressure sealing joints or connections and more particularly to an annular bore seal for sealing between first and second coaxially aligned members having opposed frusto-conical sealing surfaces tapering inwardly from their adjoining ends.
With bore seals for connectors, the sealing may be achieved by crushing or yielding the sealing element, or by elastically loading a flexible sealing element generally by utilizing a soft coating on the seal surface or by a combination of both. The seals, in some instances, are pressure energized as determined by their design and relationship with the elements to be connected. Under conditions of high pressure and high temperatures, most bore seals fail to maintain sealing capability on repeated use due to an absence or loss of elasticity under these conditions. The combination of high pressure and temperature causes an expansion of the sealing element and a tendency of the sealing element to rebound when pressure is removed. Also, such sealing elements are hardly ever reuseable because of the high degree of permanent deformation and large plastic zones which render their elements susceptible to embrittlement when exposed to hydrogen sulfide.
The present invention has, as its primary object, the provision of a high pressure bore seal with a unique metallic sealing ring which maintains elasticity at its sealing surface areas and the ability to maintain a fluidtight seal under high pressure and high temperature conditions. It is also an object to provide a bore sealing connection which provides a seal under atmospheric pressure and temperature conditions but is pressure energizable to provide enhanced sealing capability under high pressure and high temperature conditions. A further object is to provide a bore seal which is less susceptible to hydrogen sulfide embrittlement.
The invention which is a high pressure sealing connection for sealing between connected first and second coaxially aligned members comprises a metallic sealing ring having annular end surfaces at opposite ends thereof and frusto-conical outer sealing surfaces adjacent each of the end surfaces and tapering outwardly therefrom. The ring at its largest external diameter is provided with a cylindrical surface intermediate the frusto-conical sealing surfaces. At its inner periphery, the ring is formed with upper and lower flanges which extend inwardly in a substantially perpendicular relationship to the axis of the ring. The coaxially aligned members are provided with end recesses defined by opposed internal frusto-conical sealing surfaces at their adjoining ends, each tapering inwardly from the end of the member and terminating at an annular radial shoulder formed by an enlargement of the bore of the aligned member. The internal frusto-conical sealings are of equal taper in the range of 5.degree. to 20.degree. and there is a mismatch in the range of one-half degree to one and one-half degrees with the taper of the frusto-conical surfaces of the metallic sealing ring when the ring is positioned in the recesses. In unloaded condition, the initial contact of the sealing ring with the coaxially aligned members is along the upper and lower edges of the sealing ring frusto-conical surfaces. Drawing the coaxially aligned members by suitable means results in a compression of the ring which effects a fluid sealing relationship between the adjacent tapered surfaces of the ring and the aligned members which is enhanced by fluid pressure energization. The dimensions are such that a clearance gap exists in the upper and lower surfaces of the ring and the aligned members. The internal flanges of the ring significantly increase the elastic zone of the ring which includes the flanges themselves and extends from the end surfaces of the ring between plastic zones located intermediate the end surfaces and adjacent the inner and outer peripheries of the ring to provide elastic end portions of the ring. The elastic flanges continue to urge the seal ring in its sealing engagement with the aligned members even after high pressure or temperatures have caused some deformation of the sealing ring or the aligned members.